1. Field of the Invention
This invention relates generally to reflectors of electromagnetic waves, especially radar and, in particular, to a radar reflector used to calibrate shipboard and aircraft radar systems and to provide for a real time target for ship and aircraft weapons systems.
2. Description of the Prior Art
An isotropic microwave reflector is a reflector that reflects the wave back in the same direction as the incident wave regardless of the direction of the incident wave. This will occur by using corner reflectors which is the name commonly given to devices constructed with three mutually perpendicular reflecting planes whose intersection lie at a common point about an axis about which the planes are equally spaced. Incident electromagnetic energy entering the open face of the planes is reflected from two planes of the reflector in such a manner that it is returned parallel to the incident path independent of the angle of incidence of the electromagnetic energy on the reflector.
Radar reflectors and in particular corner reflectors are used with radar systems in a variety of ways such as to align the radar systems and provide measurements of the effectiveness of the radar system, and as a radar passive targets with a missile for tracking and targeting purposes. The corner reflectors constitute high reflectivity targets, that is high radar cross section targets that can be located in the radar examined field or attached to other targets to assist in location and identification of targets.
Maximum return is achieved when the incident electromagnetic wave generated by radar is targeted or aimed directly into a corner reflector. An ideal radar reflector would consist of a sphere having an infinite array of microscopic corner reflectors so as to provide for an omni-directional reflector with minimum destructive interference. However, such a design would be very costly, thus making it impractical. In the past, an omni-directional radar corner reflector has been developed wherein an array of trihedral corners, that is three planes each mutually perpendicular, are distributed on the surface of a sphere such as for example the radar reflector disclosed in U.S. Pat. No. 3,365,790. U.S. Pat. No. 4,551,726 discloses an omni-directional radar corner reflector constructed of a plurality of trihedral corner reflectors disposed in an edge to edge relationship such that when properly placed into a defined network provide the basis for constructing all members a deltatrihedral family of omni-directional radar reflectors.
Although the above described omni-directional radar reflectors have been found useful in their functional capacity, these corner reflectors do not provide for a high radar cross section which, in turn, results in a somewhat weakened radar reflection. In addition, there is for an omni-directional radar reflector which is cost effective to manufacture and is light weight so as to allow the reflector to be mounted on the mast of a target boat or the like.
It is therefore an object of the invention to provide an improved omni-directional radar reflector.
It is also an object of the invention to provide an improved omni-directional radar reflector which may be used as a target for different radar frequencies.
It is another object of the invention to provide an improved omni-directional radar reflector which reflects a greater portion of an incident electromagnetic waves than prior art devices.
It is still another object of the invention to provide an improved omni-directional radar reflector which is cost effective to manufacture and light in weight.
Other objects, advantages, novel features and applications of the invention will made apparent by the detailed description of the preferred embodiment of the invention.